Newly discovered South American scorpion sprays and injects venom, a groundbreaking first in the region. This rare species showcases a unique defense mechanism, stunning scientists and redefining arachnid behavior.
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Rare Venom-Spraying Scorpion Unearthed in Colombia – A Stunning Scientific Discovery
Rare Venom-Spraying Scorpion Unearthed in Colombia
In a groundbreaking discovery, scientists have identified the first South American scorpion species capable of spraying venom — a behavior previously observed only in two other scorpion genera found in North America and Africa.
Scorpions, renowned for their stings, use venom to immobilize prey and deter predators. Their iconic tails end in a structure called the telson, housing a venom-filled bulb and a sharp stinger known as the aculeus, which typically delivers poison through injection.
This fascinating new species, Tityus achilles, was discovered in the lush Magdalena rainforest of Colombia’s Cundinamarca department. The findings, published on December 17, 2024, in the Zoological Journal of the Linnean Society, mark a significant leap in our understanding of scorpion behavior and evolution.
“Most scorpions likely have the ability to spray venom, but they rarely do so,” explained Léo Laborieux, the study’s lead author and former master’s student at Ludwig Maximilian University of Munich. “Venom-spraying is a costly strategy, requiring intense evolutionary pressure for it to become advantageous. Something unique about the predators in this environment likely drives this behavior.”
This remarkable defense mechanism parallels strategies seen in other creatures, such as spitting cobras, which also spray venom to deter threats. Such externally applied toxins, called toxungens, are used by a variety of species — from arthropods to mammals — for defense and occasionally hunting. These toxins may be sprayed, smeared, or even passively transmitted to adversaries.
The discovery of Tityus achilles sheds light on the complexity of evolutionary adaptations, offering new insights into the interplay between predators and prey in South America’s biodiverse ecosystems. It also underscores the importance of conserving habitats where such unique behaviors can continue to be studied.
The scorpion is able to deliver venom via it's stinger, as well as a pre-venom secretion (seen in white on the scorpion's body). (Image credit: Léo Laborieux/Zoological Journal of the Linnean Society, 2024)
Unlike many organisms that employ toxungens, the newly discovered Tityus achilles scorpion stands out as both toxungenous and venomous. While poisonous creatures transmit toxins through ingestion or external contact, venomous animals deliver their toxins through specialized organs, such as fangs or stingers. Remarkably, T. achilles can do both — injecting its venom or spraying it.
Direct injection ensures the venom is delivered effectively, allowing the scorpion to subdue prey or defend itself. However, this method comes with physical risks. Engaging in close contact with a predator or struggling prey increases the likelihood of retaliation.
Spraying venom, on the other hand, minimizes physical danger. By maintaining a safe distance, the scorpion reduces the chance of injury. However, spraying is less precise and delivers milder effects compared to an injected sting. Even so, a well-aimed squirt of toxin can be enough to repel predators and provide the scorpion an opportunity to escape.
Interestingly, T. achilles appears to have a targeted approach when spraying venom. The angle of its spray suggests it is directed at sensitive areas such as the eyes or nose of its attackers. This strategic targeting increases the chance of the toxin reaching vulnerable tissues and effectively deterring threats.
“These toxins need to reach very sensitive tissues to actually take effect,” explained Léo Laborieux, the researcher behind the discovery. “For this to make sense, the predator has to be a vertebrate.” He noted that the venom’s effects would be ineffective against the tough exoskeletons of invertebrates, indicating that spraying is likely a defense mechanism rather than a hunting tool.
This dual venom-delivery system highlights the fascinating adaptations of Tityus achilles and underscores its unique role in the ecological dynamics of the South American rainforest.
T. achilles appears to use its venom spray as a defense mechanism against predators. (Image credit: Léo Laborieux/Zoological Journal of the Linnean Society, 2024)
To test the venom-spraying ability of Tityus achilles, Léo Laborieux conducted experiments using an unconventional tool: a drinking straw. By gently pinning the scorpions, he was able to observe and record their defensive reactions. Over the course of his tests, Laborieux examined 10 juvenile scorpions and documented 46 venom ejections, with the spray reaching an impressive maximum distance of 14 inches (36 centimeters).
The scorpions demonstrated two distinct responses: some flicked small venom droplets toward the perceived threat, while others unleashed a sustained spray. Most venom ejections were directed forward, but occasionally, sprays were aimed backward or upward, highlighting the scorpion’s flexibility in targeting potential predators.
Interestingly, the majority of these venom ejections were transparent, which Laborieux identified as pre-venom — a less potent but still toxic liquid. True venom, in contrast, has a milky appearance due to its higher concentration of complex peptides and proteins.
“The venom itself is usually composed of higher molecular weight peptides and proteins, which are much larger and, as a result, much more expensive to produce,” Laborieux explained.
By utilizing pre-venom in its initial defense, T. achilles employs a cost-effective strategy. For a small organism reliant on these compounds for both defense and hunting, conserving resources is crucial, especially given the high likelihood of encountering multiple predators in its environment.
This innovative use of pre-venom adds another layer of complexity to the behavior of Tityus achilles, further cementing its place as a fascinating subject of study in South America’s biodiversity.